Tool forging method



' Nov. 8, 1938. NAST TOOL FORGING METHOD Filed Jan. 30, 1954 2 Sheets-Sheet 1 Nov. 8, 1938. P. H. NAST TOOL FORGING METHOD v 2 Sheets-Sheet 2 Filed Jan. 50, 1954 15206722 01? PauZH/Vaaifi Patented Nov. 8, 1938 UNITED STATES PATENT OFFICE TOOL FORGING METHOD Massachusetts Application January 30, 1934, Serial No. 708,996

Claims.

This invention relates to tool forging methods,

and more particularly to improved methods of forming the cutting bits of rock drill steels.

In forming the cutting bits of rock drill steels, 5 it is customary to swage the sides of the bit wings prior to the upsetting operation. In swaging, the forward ends of the wings of the bit have usually been formed with plane surfaces at a.70 angle, and thus a clearance is provided, when the bit is placed in a 90 angle dolly, so that the metal may flow on upsetting to a sharp edge. During upsetting, the wing sides are formed with plane surfaces at anangle of 90, and the clearance above mentioned is provided so that the cutting edge is upset more readily when bringing the wing shape back from the 70 angle to the 90 angle of the wings. However, it has been found that even with this process upsetting does not uniformly produce a sharp edge; and I have found that if the wing sides are formed with concave surfaces instead of the plane surfaces at a 70 angle prior to the upsetting operation, the cutting edge is formed more easily and surely during upsetting, since there is more clearance and less metal to flow to obtain the desired shape of cutting edge with piane wing surfaces at a 90 angle. Concave wing surfaces are of particular importance in resharpening steels wherein the cutting edges are rounded down by wear, since the 7()- plane surfaces on the wings do not sufficiently draw out the metal so that proper upsetting is possible.

An object of this invention is to provide improved tool forging methods for forming the cutting bits of rock drill steels. Another object is to provide improved forging methods whereby the cutting edges of a drill steel bit are formed in an improved manner. A further object of this invention is to provide improved methods for shaping the wings of a cross bit prior to the upsetting operations so that the latter operation may be accomplished more readily and in an improved manner. Yet another object is to provide improved forging methods whereby the cutting edges of such bits are formed by concaving the sides of the bit wings prior to the .upsetting operation, thereby improving the cutting edges obtained. Still another object is to provide an improved method of making drill bits. These and other objects and advantages of the invention will, however, hereinafter more fully appear.

In the accompanying drawings there is shown for purposes of illustration one form which the invention, as a structure, may assume in practice, and one method of practicing it from its aspect as an art.

In these drawings,

Fig. 1 is a side elevational View of the illustrative form of improved forging dies, with a rock drill steel in forging position therein.

Fig. 2 is a plan view of Fig. 1, with the upper die removed.

Fig. 3 is a diagrammatic View showing a bit wing in an intermediate stage of sharpening in accordance with a former method.

Fig. 4 is a diagrammatic view showing a bit in an intermediate stage of being formed by the improved method.

Fig. 5 is a detail view showing the upsetting dolly and steel-clamping blocks of the forging machine with which the improved forging dies are used.

Fig. 6 is a perspective view of the improved forging dies.

In this illustrative embodiment of the invention there is shown a pair of die blocks I and 2 of which the lower die block 2 is adapted to be supported in a stationary anvil block of a drill steel forging machine of a standard design, while the upper die block i may be carried by a reciprocating hammer member and caused to be moved toward and from the stationary die block 2 with a rapid hammering action, or may be held by suitable means in proper position relative to the lower block and percussively actuated; it being a well known fact that rock drill bits are usually sharpened by a hammering process combined with a dollying process for the purpose of forming the wings 3 of the bit of a standard rock drill steel 4. These improved swaging dies-are provided with swaging surfaces 5 and 6, respectively, and grooves and B to receive the more or less finished wings, these grooves being so formed as to receive and shape the outer longitudinal surfaces of the wings which are not being swaged laterally. These wing-forming grooves open out laterally through the sides of the bit blocks at 9 to permitv the escape of scale or other foreign substances from between the die surfaces. During the swaging operation heretofore common, the wings of the bit have been formed with plane surfaces at a angle, as indicated at H] in Fig. 3, and thereafter during the dollying or upsetting process the 70 angle surfaces of the wings have been upset by the dolly to the plane surfaces, as indicated at II in Fig. 3, to provide a cutting edge at I 2 but, as above mentioned, it has heretofore been found that, particularly when the drill bits are being resharpened, the surfaces on the die blocks did not properly form the wing surfaces from the 70 angle shown at In in Fig. 3 to the desired cutting shape of 90 indicated at l I in Fig. 3.

In order to overcome this disadvantageous feature, the improved die blocks shown herein are provided with convex surfaces I3 and I4, so that during the swaging operation the wings of the bit are formed with concave surfaces, as indicated at I5 in Fig. 4, that is the surfaces or wings are formed in the manner indicated in full lines in Fig. 4 in place of the usual 70 angle surfaces If! indicated in full lines in Fig.7 3, the surfaces of the bit wings, after the swaging operation, assuming the form shown in Fig. 2. The dihedral angles in whose sides lie the intersections and the rearward extremities of the inclined sides of the wings may be said to be of less angular inclusion than the dihedral angle of the finished bit. Evidently the die surfaces l3 and M will cooperate to form at the projected (i. e. planned) cutting end of a bit a pair of concave surfaces intersecting in a line in advance of the intended ultimate edge of the tool and having the elements thereof parallel to such a line.

After the swaging operation has been completed, the drill steel is placed between clamping blocks it and IT, as shown in Fig. 5, of the forging machine, and rigidly clamped in position therebetween. The dolly l8 of the sharpening -machine, whose sides form a dihedral angle of greater inclusion than the dihedral angle first above mentioned, is then percussively actuated so as to hammer the concaved surfaces of the bit wings. With this form of concave surfaces on the bit wings, there is ample clearance between the 90 angle forming surfaces IS on the dolly face so that the metal of the bit readily flows into a shape to conform with the 90 angle surfaces of the dolly, the surfaces of the wings being formed from the shape indicated in full lines in Fig. 4 to the proper 90 angle cutting shape with sharp edge as indicated at l l in construction lines in Fig. 4. It will thus be seen that the convex surfaces of the swaging dies will form a concave impression on the bit Wings which allows more working clearance during the upsetting operation so that the cutting edge is upset more readily when bringing the wings back to" the proper 90 shape.

As a result of this invention, it will be noted that improved methods are provided for forming the cutting bit of a rock drill steel prior to the upsetting operation so that upsetting is more readily accomplished and the cutting edges are formed in an improved manner. It will further be noted that by forming the forging dies with convex surfaces so that the wings of the cutting bit are formed with concave surfaces, the metal in the wings of the bit flows into proper shape in an improved manner during the upsetting operation and with less work and wear on the part of the dollying mechanism. Theseand other uses and advantages of the improved forging method will be clearly apparent to those skilled in the art.

While there is in this application specifically described one method of practicing the invention, it will be understood that this is done for purposes of illustration and that the invention may be modified and otherwise practiced without departing from its spirit or the scope of the appended claims.

What I claim is new and desire to secure by Letters Patent is:

l. The method of forming cutting edges of a cross bit comprising initially swaging the wing surfaces of the bit into a concave form and thereafter upsetting the wing surfaces by a dollying process to increase the angle adjacent the cutting edge.

2. The method of forming cutting edges on a cross bit comprising initially swaging the wings with the forward and rear extremities of their tapered portions at the edge and in the sides of a dihedral angle of 'less than the desired angle of the finished bit, and with the surfaces of the tapered portions concave, and upsetting said tapered portions with a dolly grooved to form a dihedral angle of the desired finished shape.

3. The method of forming the cutting end of a tool to provide a cutting edge at the'intersection of surfaces diverging rearwardly from said cutting edge, comprising initially forming at the end of said tool a pair of concave surfaces intersecting at an angle less than the ultimate desired angle between the diverging surfaces of the finished end, and upsetting said end with die means having material-working intersecting surfaces diverging from their intersection at a greater angle than the angle at the end of the partially formed tool.

4. The method of forming the cutting end of a tool to provide a cutting edge at the intersection of surfaces diverging rearwardly from said cutting edge, comprising initially forming at the end of said tool a pair of concave surfaces intersecting in a line in advance of the ultimate desired cutting edge of the finished end, and upsetting said end with die means having materialworking intersecting surfaces diverging from their intersection at a greater angle than the angle at the end of the partially formed tool.

5. The method of forming the cutting end of a tool to provide a cutting edge at the intersection of surfaces diverging rearwardly from said cutting edge, comprising initially forming at the end of said tool a pair of concave surfaces intersecting at an angle less than the ultimate desired angle between the diverging surfaces of the finished end and in a line in advance of the ultimate desired cutting edge of the finished end, and upsetting said end with die means having material-working intersecting surfaces diverging from their intersection at a greater angle than the angle at the end of the partially formed tool.

PAUL H. NAST. 

